ABSTRACT
The passage of agricultural and forest machines over soil is the main cause of compaction of
cultivated and forest soils. If the load applied during trafficking is larger than the resistance
of the soil against compaction (mechanical soil strength), compaction of the soil occurs.
Compaction (also referred to as compression) is a reduction of the volume of a given mass of
soil. The decrease in soil volume is due to a decrease in the volume of pore space through
partial expulsion of soil air and water. When soil is compacted, the porosity is decreased and,
conversely, the bulk density is increased. The decrease in porosity due to compaction is
accompanied by a modification of the pore geometry, i.e., pore morphology and connectivity.
Hence, soil compaction modifies soil structure. Pore geometry, which may also be strongly
affected by shearing, is a very important component of soil structure because it greatly
affects the properties of water and gas transport in soil.
